I used to think my Raytek was accurate but someone shot my stuff with a bluepoint (snap on) and it's 40 degrees different. but his gun looked like it was thrown around in a garage for 6-10 years already. full of grease and oil etc. and I've tested mine against a contact type pyrometer and it reads the same as it but that was about 8 years ago.

but I would love to find someone with a exergen and see who's is closer.
the exergen while so over inflated priced is the only ir gun in the world certified accurate by nist .